Dry‐etching‐assisted femtosecond laser machining

• Published in: Laser & photonics reviews Vol. 11; no. 3
• Main Authors: Liu, Xue‐Qing, Chen, Qi‐Dai, Guan, Kai‐Min, Ma, Zhuo‐Chen, Yu, Yan‐Hao, Li, Qian‐Kun, Tian, Zhen‐Nan, Sun, Hong‐Bo
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-05-2017
• Subjects: concave microlens; dry etching; femtosecond laser; Laser machining; micronanofabrication; silicon
• ISSN: 1863-8880; 1863-8899
• DOI: 10.1002/lpor.201600115

Femtosecond laser machining has been widely used for fabricating arbitrary 2.5 dimensional (2.5D) structures. However, it suffers from the problems of low fabrication efficiency and high surface roughness when processing hard materials. To solve these problems, we propose a dry‐etching‐assisted femtosecond laser machining (DE‐FsLM) approach in this paper. The fabrication efficiency could be significantly improved for the formation of complicated 2.5D structures, as the power required for the laser modification of materials is lower than that required for laser ablation. Furthermore, the surface roughness defined by the root‐mean‐square improved by an order of magnitude because of the flat interfaces of laser‐modified regions and untreated areas as well as accurate control during the dry‐etching process. As the dry‐etching system is compatible with the IC fabrication process, the DE‐FsLM technology shows great potential for application in the device integration processing industry.
Dry‐etching‐assisted femtosecond laser machining technology is proposed for fabricating complex microstructures. As an example, a silicon concave microlens array could be successfully fabricated. The morphology of microstructures could be flexibly adjusted by controlling the activation and passivation effect. The combination of the three‐dimensional fabrication property of femtosecond lasers with the precision processing of dry etching would develop a new fabrication technology.